Communication has become an ever increasing part of day-to-day life, both in business and personal lives. Accordingly, various forms of communication devices have become nearly ubiquitous. For example, a very large portion of the world's population have and utilize mobile devices, such as cellular telephones, personal communication system (PCS) phones, personal digital assistants (PDAs), smart phones, personal computers (PCs), etc., to provide voice and/or data communication. To provide highly mobile operation, such mobile devices often operate wirelessly to communicate with a host network. Thus, the mobile devices may be, for example, portable, pocket, hand-held, computer-included, or car-mounted devices which communicate voice and/or data wirelessly via a host radio network. Of course, such mobile devices can be fixed mobile devices, e.g., fixed cellular devices/terminals which are part of a wireless local loop or the like.
Cellular networks are well known for providing communications with respect to various mobile devices. In a typical cellular network, mobile devices communicate via a radio access network (RAN) to devices coupled to the cellular network. The RAN traditionally covers a geographical area which is divided into cell areas, with each cell area being served by a base station. The area coverage of such a base station, or cell area, is sometimes referred to as a macrocell. The base stations communicate over an air interface (e.g., radio frequencies) with the mobile devices or other mobile devices within range of the base stations. These base stations are typically positioned to bring the greatest coverage to the greatest number of cellular telephone users.
In the RAN, several base stations are typically connected (e.g., by landlines or microwave) to a radio network controller (RNC). The RNC, also sometimes termed a base station controller (BSC), supervises and coordinates various activities of the plural base stations connected thereto. The RNCs are typically connected to one or more systems (e.g., a mobile switching center (MSC)) providing the core communication services (e.g., call connect, call accounting, enhanced telephony services (ETSs) such as voice mail, one number service, call back service, language translation, call waiting, three-way calling, caller ID, do not disturb, and call forwarding service, public switched telephone network (PSTN) interfacing, etc.).
One example of a RAN is the universal mobile telecommunications (UMTS) terrestrial radio access network (UTRAN). The UMTS is a third generation system which in some respects builds upon the radio access technology known as global system for mobile (GSM) developed in Europe. UTRAN is essentially a RAN providing wideband code division multiple access (WCDMA) to mobile devices. Other types of cellular telecommunications systems which encompass RANs include, but are not limited to GSM systems, advance mobile phone service (AMPS) systems, narrowband AMPS (NAMPS) systems, total access communications system (TACS) systems, personal digital cellular (PDC) systems, United States digital cellular (USDC) systems, and code division multiple access (CDMA) systems (e.g., as described in EIA/TIA IS-95).
Cellular networks such as those described above are referred to herein as a “mobile core network” (or simply “mobile core”) and typically provide a circuit switched network. It should be appreciated that, although terms typically associated with particular network standards and protocols have been used in describing exemplary mobile core networks above, mobile core networks as discussed herein may comprise various configurations, such as GSM, CDMA, time division multiple access (TDMA), UMTS, second generation (2G), third generation (3G), high speed packet access (HSPA), time division-synchronous code division multiple access (TD-SCDMA), time division-code division multiple access (TD-CDMA), etc. The makeup and functionality of these and other mobile core networks is well-known in the art and is thus not described further herein.
It should be appreciated that, in a traditional cellular network, the coverage of the macrocell base stations is often not uniform. For example, individual buildings (e.g., homes, offices, etc.) may have weak signals indoors. Accordingly, more recently the addition of femtocell base stations (sometimes referred to as “home base stations,” “access point base stations,” “3G access points,” “small cellular base stations,” and “personal 2G-3G base stations”) has evolved.
In general, a femtocell base station is a small cellular base station designed for use in residential or small business environments. It connects to the service provider's network via a broadband packet switched network (such as using digital subscriber line (DSL), asymmetric digital subscriber line (ADSL), or cable internet) and typically supports 1 to 5 mobile devices (e.g., telephones) in a residential or business setting. In general, the femtocell incorporates the functionality of a typical base station but extends it to allow a simpler, self-contained deployment.
A femtocell base station allows service providers to extend service coverage within a targeted small geographic location, such as within a user's home or business—especially where access would otherwise be limited or unavailable—without the need for an expensive traditional cellular base station to be added to provide communication services for use by a small number of mobile devices. That is, although there may be hundreds or thousands of areas in which the mobile core network does not provide adequate coverage for communication services, each such area may have a very few mobile devices operated therein. Deploying a relatively small and inexpensive femtocell base station, leveraging a readily available broadband packet switched network such as the Internet to provide a communication link to the mobile core network, facilitates economic mobile device communications within these areas otherwise unserved or inadequately served by traditional macrocell base stations.
A femtocell base station may thus be deployed directly within a wireless subscriber's premises, such at a home or office. With a femtocell base station, the wireless communication device (e.g., cellular telephone) accesses the femtocell base station through traditional licensed spectrum. However, using such femtocell base stations, connectivity to the mobile core network is provided through the packet switched network using voice over internet protocol (VoIP) and/or internet protocol multimedia subsystem (IMS) technologies.
As can be appreciated from the foregoing, communication protocols and processing paths that are used in a network implementing a packet switched network (e.g. a femtocell), are different than those traditionally used for communication with the mobile core network. As a result, difficulties arise when a mobile device attempts to hand-in or hand-out between a femtocell and a macrocell.
Current solutions deployed in the market to address hand-in/hand-out difficulties do not support a hand-in to the femtocell network from a macrocell network, or a hand-out of the femtocell network to a macrocell network, while a mobile device is on an active call. As a result, an ongoing active call will be dropped either when a user is coming into the femtocell or leaving the femtocell.
One proposed solution to enable hand-in and hand-out of a mobile device during an active call is a voice call continuity (VCC) based approach. VCC approaches require mobile devices to be able to support concurrent calls on a mobile core network and on a packet switched network. Because the VCC based approach forces the mobile device to use its resources to support a redundant connection on two networks, needless overhead is created and devices must possess additional functionality to enable them to communicate on both networks simultaneously. In other words, mobile devices implementing a VCC approach can not be legacy devices (e.g. mobile devices adapted for mobile core network communications without specific adaptation for such communications to be provided via a packet switched network). Another limitation of the VCC solution is that in order to seamlessly hand off a call, the call must always be routed through a VCC server due to the inability to predict when a mobile device will enter or exit a femtocell or macrocell. As a result, even on a call that is between devices that are transmitting solely on a mobile core network, the call must be routed through the VCC server, thereby inserting inefficiency.
Another issue that results from differing protocols used in networks implementing a femtocell and those traditionally used for communication with a mobile core network is apparent when attempting to identify users within the different networks. In a packet switched network, or especially in an IMS network, users are often identified using a session initiation protocol (SIP) identifier or other identifier, which is similar to an email address (e.g. user@IMS.Tatara.com). Whereas in a mobile core network, users are typically identified using an MDN, which is a 10-digit mobile number. A packet switched network is not aware of the MDN and a mobile core network is not aware of the packet switched network public user identity. This introduces a problem because a user gets registered in the packet switched domain using the public user identity, whereas the real identity of that macro user is the MDN. So moving forward, if the carrier wants to handoff of the packet switched network's services, then it would need to know the MDN of the user.
Currently, if the MDN of the user is not known, in order to allow handoff of the packet switched network's services, the information must be downloaded from a visitor location register (VLR). So there is a disconnect between the databases of the differing networks. Another problem is if a user that is subscribed to an access point in a packet switched network (e.g. a femtocell) has moved onto another service provider network, for example from Sprint to Verizon, then the subscriber would need to be deleted from two separate databases, the home location register (HLR) database, and the home subscriber server (HSS) database. Therefore, currently there are two databases that need to be maintained for a femtocell subscriber being served.